package com.wc.alorithm_blue_bridge_history.simulation_match3.F;

import java.util.Scanner;

/**
 * @Author congge
 * @Date 2024/3/8 15:25
 * @description
 * https://www.lanqiao.cn/problems/16569/learning/?problem_list_id=29&page=1
 */
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println((n + 2) / 3);
    }
}

